Stock-based compensation expense was allocated as follows:


	Three Months Ended March 31,
	2023		2022
Cost of revenues	$	124	$	124
Sales and marketing		165		175
Research and development		270		224
General and administrative		473		334
Total	$	1,032	$	857

For stock-based awards granted by the Company, stock-based compensation cost is measured at grant date based on the fair value of the award and is expensed over the requisite service period. Stock-based compensation capitalized as internally developed software was $37 and $26 for the three months ended March 31, 2023 and 2022, respectively.

There were no grants or exercises of stock options during the three months ended March 31, 2023 and 2022.

Compensation expense, net of forfeitures, is recognized ratably over the requisite service period. As of March 31, 2023, unrecognized compensation expense related to stock options was immaterial.

As of March 31, 2023, there was $4,293 of unrecognized compensation expense related to RSUs, which is expected to be recognized over a weighted-average period of 1.6 years. The Company uses the fair market value of the underlying common stock on the dates of grant to determine the fair value of RSUs.

The Company estimates the fair value of purchase rights under the 2013 ESPP using the Black-Scholes valuation model. The fair value of each purchase right under the 2013 ESPP is estimated on the date of grant using the Black-Scholes option valuation model and the straight-line attribution approach with assumptions substantially similar to those used for the valuation of stock option awards, with the exception of the expected life. The expected life is estimated to be six months, which is consistent with the purchase periods under the 2013 ESPP.